Oh, an even DIFFERENT form factor-is this an NLX case? Where a full height AGP card is mounted with the VGA connector ABOVE some connectors on the back? With a notch in the bottom of the card between the slot and the backplate? In that case there are a few more options available.
For instance, the Diamond Viper V770 and V770 Ultra both have a break-out section between the slot and the back plate for use in NLX systems. These are TNT2 and TNT2 Ultra cards and perform fairly well (much better than an MX200). You might find a GTS or MX400 card with the same layout, I'm not sure, but if you can't find something better, the V770 and V770 Ultra are reasonable choices. Nothing in PCI even comes close (due to the limited bandwidth of PCI).
What's the frequency, Kenneth?